Suction Jet Pump

ABSTRACT

The invention relates to a suction jet pump ( 12 ), composed of a housing ( 18 ) having a connection ( 24 ), a propellant line ( 14 ), a propulsion jet nozzle ( 19 ), a mixing tube ( 15 ) which adjoins said propulsion jet nozzle ( 19 ), and a suction point ( 13 ) arranged upstream of the mixing tube ( 15 ). In addition, the suction jet pump ( 12 ) has a second suction point ( 16 ).

The invention relates to an eductor-jet pump, comprising a housinghaving a connection of a motive fluid line, an eductor jet nozzle, anadjoining mixing tube and a suction point located upstream of the mixingtube. Such eductor-jet pumps are used in fuel tanks of motor vehicle, inorder to deliver fuel from different areas of the fuel tank to a fuelpump located in the fuel tank.

Eductor-jet pumps of the aforementioned type are used inmultiple-chamber tank systems, in which the fuel tank has at least twochambers, so as to be able to drain all chambers as efficiently aspossible, especially in the event of a low filling level in the fueltank. A distinction is made between two types of eductor-jet pump. Thefirst type draws in fuel more or less directly through a suction point.For this purpose the eductor-jet pump is located at the point from whichthe fuel is pumped. The second type of eductor-jet pumps are suctioneductor-jet pumps, the suction point of which is connected to a suctionline. The suction line is carried into the area from which the fuel isto be pumped. Apart from the somewhat higher costs of generating asufficient vacuum for the suction line, this type of eductor-jet pumphas the advantage of being independent of the site from which fuel is tobe pumped. A disadvantage of both types of eductor-jet pump is that thenumber of eductor-jet pumps needed is equal to the number of chambers tobe drained. Despite their relatively simple construction, the cost ofparts and assembly is considerable.

The object of the invention is to reduce the cost of draining a fueltank having multiple chambers or areas to be drained.

According to the invention the object is achieved in that theeductor-jet pump has a second suction point.

Providing a second suction point creates an eductor-jet pump withpassive secondary suction, which does not need an additional drive inthe form of a further motive jet. In this way it is possible to halvethe number of eductor-jet pumps required for a multiple-chamber fueltank. This leads, in particular to a considerably reduced assembly cost.The efficiency of the overall fuel delivery system is furthermoreimproved, since obviating the need for a motive jet for the secondsuction point means that the fuel pump needs to provide less hydraulicpower for driving the eductor-jet pump. The hydraulic power saved caneither be delivered to the internal combustion engine of the motorvehicle as additional fuel delivery, or the fuel pump can be of smallerdimensions. The eductor-jet pump with passive secondary suction isparticularly effective in the case of small fuel delivery quantities.

The second suction point is especially easy to configure if the suctionpoint opens into the mixing tube of the eductor-jet pump.

The design arrangement of the second suction point on the eductor-jetpump, particularly on the mixing tube, is relatively easy to configureif it has a smaller cross section than the first suction point. Assuminga first suction point cross section in the order of 100 mm²-200 mm², thesecond suction point may be up to 100 times smaller in cross section.

A suction line can be fitted to the second suction point with littleeffort if the second suction point opens into a diffuser of the mixingtube, the diffuser being arranged on the side of the mixing tube remotefrom the eductor jet nozzle.

With a diffuser of small axial length the arrangement of the secondsuction point can sometimes prove difficult. It has therefore provedadvantageous to have the second suction point opening out in a section,preferably a cylindrical section, of the mixing tube situated upstreamof the diffuser. This section has a sufficient axial length, whichallows the second suction point to be located without any problems.

In another embodiment the second suction point is arranged in the areaof the first suction point relative to the axial extent of theeductor-jet pump, preferably in the housing of the eductor-jet pump. Inthis embodiment the mixing tube remains unaltered, making it possible touse existing forms of mixing tube. Another advantage is that eductor-jetpumps, which are fitted via the mixing tube, by inserting it togetherwith the mixing tube, for example, into a swirl pot, can be fittedwithout modification. The second suction point therefore has no effecton the fitting of the eductor-jet pump.

The second suction point is located on the periphery of the eductor-jetpump at an angle of 20° to 180°, preferably between 90° and 180°, to thefirst suction point. By purposely selecting the angle, the eductor-jetpump can thereby be readily adapted to the given installation geometry.

Large angles in the order of 180° between the two suction points haveproved advantageous when the first suction point is oriented verticallydownwards in the installation position of the eductor-jet pump, and thescope for installation in a horizontal direction is limited. The suctionline of the second suction point in this case leads basicallyperpendicularly to the eductor-jet pump. A large angle is furthermoreadvantageous when the eductor-jet pump is arranged between two areasfrom which fuel is to be drawn. The two suction points are then orientedsubstantially horizontally. Unnecessary deviations of the suction linesare therefore avoided.

A small angle is advantageous when the areas from which the eductor-jetpump is to draw fuel lie in one direction relative to the eductor-jetpump, or both suction lines have to be laid in one direction owing tothe space available in the fuel tank.

In an eductor-jet pump manufactured by injection molding, a good moldrelease and hence simply designed dies are achieved if the secondsuction point is arranged with its axial extent perpendicular to theaxial extent of the eductor-jet pump.

A reduction in the overall radial extent is achieved in anotherdevelopment with an eductor-jet pump in which the second suction pointis arranged with its axial extent at an angle to the axial extent of theeductor-jet pump that deviates from the perpendicular.

The second suction point can be produced especially cost-effectively ifit is integrally formed with the eductor-jet pump. A housing or aneductor-jet pump formed in this way is particularly cost-effective tomanufacture owing to the good mold release facility, especially wherethe second suction point is arranged at an angle of 180° to the firstsuction point.

In one simple development the second suction point is embodied as aconnection, to which a line in the form of a suction line can beconnected.

In another development the second suction point is embodied as a bore,into which a line in the form of a suction line can be inserted.

The connection of the motive fluid line is arranged radially or axiallyin relation to the axial extent of the eductor-jet pump, according tothe installation conditions. In the case of eductor-jet pumps having aradial connection of the motive fluid line, an embodiment of theeductor-jet pump in which the second suction point has the same radialorientation as the connection has proved advantageous. For one thing,such an eductor-jet pump takes up little overall space in a radialdirection. For another, such an eductor-jet pump can be cost-effectivelymanufactured by injection molding, the dies being of especially simpledesign, due to the fact that the connection and the second suction pointboth have the same radial orientation and the demolding directionassociated therewith is shared.

According to a further development a wider scope for adapting theeductor-jet pump according to the invention to various installationconditions is achieved by means of a separate diffuser, which isdesigned for connection to the mixing tube. The radial position of thesecond suction point is fixed and therefore adapted to the actualinstallation situation according to the radial orientation of thediffuser in the assembly with the remainder of the mixing tube. Such aneductor-jet pump is therefore versatile in use. The connection of thediffuser to the remainder of the mixing tube is especially easy to makeas a snap socket connection. It is also feasible, however, to connectthe diffuser to the remainder of the mixing tube by means of a welded oradhesively bonded connection.

The invention will be explained in more detail with reference to severalexemplary embodiments. In the drawing:

FIG. 1 shows the arrangement of an eductor-jet pump in a fuel tank,

FIG. 2 shows a section through an eductor-jet pump according to theinvention and

FIGS. 3-6 show further embodiments of the eductor-jet pump according toFIG. 2.

The fuel tank 1 represented in FIG. 1 comprises two chambers 2, 3, whichare connected together via a saddle 4. A fuel supply unit 5, which isfitted into the fuel tank 1 via an opening 7 closed by a flange 6, isarranged in the chamber 2. The fuel supply unit 5 comprises a swirl pot8, in which a fuel pump 9 is arranged. Fuel drawn out of the swirl pot 8by the fuel pump 9 via a pump pre-filter 10 is delivered via a feed line11 though the flange 6 to an internal combustion engine (not shown).

For filling the swirl pot 8, an eductor-jet pump 12, which draws fuelfrom the fuel tank 1 via a first suction point 13 and delivers it intothe swirl pot 1, is arranged in the base area of the swirl pot. Theeductor-jet pump 12 is driven by a motive fluid line 14 with fueldelivered by the fuel pump 9. Whilst in the representation shown themotive fluid line 14 branches off from the feed line 11, it is alsofeasible to feed the motive fluid line 14 directly from the pump stageof the fuel pump 9.

In the area of the mixing tube 15 the eductor-jet pump 12 has a secondsuction point 16, which is connected to a suction line 17. The suctionline 17 is carried into the base area of the chamber 3, so that inoperation of the eductor-jet pump 12 fuel is delivered from the chamber3 into the swirl pot 8.

FIG. 2 shows the eductor-jet pump 12 from FIG. 1. The eductor-jet pump12 has a common housing 18, which links the various areas of theeductor-jet pump 12 together to form an integral structure. An eductorjet nozzle 19 with a nozzle opening 20, which is oriented axially to themixing tube 15, is arranged in the housing 18. The mixing tube 15comprises an inlet area 21, and a cylindrical section 22, adjoiningwhich is a downstream diffuser 23. A first suction point 13 as primarysuction is arranged upstream of the mixing tube 15 in the direction offlow. In the horizontal installation position of the eductor-jet pump 12shown, the first suction point 13 is oriented vertically downwards.

The eductor jet nozzle 19 is integrally connected to a connection branch24, which at its end remote from the eductor jet nozzle 19 is providedwith a pine-tree profile for connection of the motive fluid line 14 (notshown). The connection branch 24 is arranged on the periphery of theeductor-jet pump 12 perpendicular to the axial extent of the eductor-jetpump 12 and at an angle of 180° to the first suction point 13. Anopening in the eductor jet nozzle 19, made opposite the nozzle opening20 for production reasons, is closed by means of an impressed ball 25.

The cylindrical section 22 has a connection 26, which in a similar wayto the branch connection 24 is arranged on the periphery of theeductor-jet pump 12 perpendicular to the axial extent of the eductor-jetpump 12 and at an angle of 180° to the first suction point 13. Connectedto the connection 26 is the suction line 17 (not shown), the connection26 forming the second suction point 16. For arranging the suction line17 on the connection 26, the latter may be designed with a pine-treeprofile like the branch connection 24.

When fuel is delivered to the eductor-jet pump 12 via the motive fluidline it emerges via the nozzle opening 20 and enters the mixing tube 15.In so doing the fuel emerging from the nozzle opening 20 generates anegative pressure in the area of the first suction point 13, with theresult that fuel is drawn out of the fuel tank by this primary suctionat the first suction point 13 and is delivered via the mixing tube 15into the swirl pot. Delivering the fuel through the mixing tube 15likewise generates a negative pressure in the connection 26 of thesecond suction point 16, with the result that fuel is drawn out of theother chamber of the fuel tank via the suction line and delivered intothe swirl pot.

In construction, the eductor-jet pump 12 in FIG. 3 differs from theeductor-jet pump in FIG. 2 in that the connection branch 24 is arrangedcoaxially with the horizontal extent of the eductor-jet pump 12. In thehousing 18 the connection 26 of the second suction point 16 is arrangedin the area of the first suction point 13, relative to the axial extent.The connection 26 is in turn arranged on the periphery of theeductor-jet pump 12 perpendicular to the axial extent of the eductor-jetpump 12 and at an angle of 180° to the first suction point 13.

FIG. 4 shows a sectional top view of an eductor-jet pump 12, the basicconstruction corresponding substantially to the eductor-jet pumpaccording to FIG. 3. The eductor-jet pump 12 has a horizontal connectionbranch 24, which merges into the housing 18. The first suction point 13is again situated on the underside of the eductor-jet pump 12, so thatit is hidden by the eductor jet nozzle 19. In contrast to FIG. 3, theconnection 26 of the second suction point 16 is arranged on theperiphery of the eductor-jet pump 12 at an angle of 90° to the firstsuction point 13 and therefore in the plane of projection. Theeductor-jet pump 12 thereby has an especially low overall height in avertical direction. The connection 26 is arranged at an angle deviatingfrom the perpendicular in relation to the axial extent of theeductor-jet pump 12, the angle a between the axial extent of theeductor-jet pump 12 and the axial extent of the connection 26 being 55°.

FIG. 5 shows an eductor-jet pump 12 having a basic constructionaccording to FIG. 3. The second suction point 16 is arranged in the areaof the diffuser 23 and takes the form of a bore 27, in which the suctionline (not shown) is fixed by insertion.

The eductor-jet pump 12 in FIG. 6 shows a further embodiment of theeductor-jet pump according to FIG. 5. The diffuser 23 has a connection26 as second suction point 16, the diffuser 23 being designed as aseparate component. On its side facing the mixing tube 15 the diffuser23 has a radial circumferential groove on its inside diameter. Thisinteracts with a bead 28 running radially around the outside diameter ofthe mixing tube 15. The clip connection thus formed allows the diffuser23 to be fixed to the mixing tube 15. The radially circumferentialdesign of the groove and the bead 28 allows the connection 26 to beoriented radially at any angle perpendicular to the axial extent of theeductor-jet pump 12.

1.-13. (canceled)
 14. An suction jet pump, comprising: a housing, havinga connection to a motive fluid line, an ejector nozzle, a mixing tubeadjoining the ejector nozzle, a first suction point located upstream ofthe mixing tube for receiving fluid to pumped, and a second suctionpoint for receiving fluid to be pumped.
 15. The suction jet pump ofclaim 14, wherein the second suction point opens into the mixing tube.16. The suction jet pump of claim 15, further comprising a diffuser on aside of the mixing tube remote from the ejector nozzle, the secondsuction point opening into the diffuser of the mixing tube.
 17. Thesuction jet pump of claim 14, further comprising a diffuser on a side ofthe mixing tube remote from the ejector nozzle, wherein the secondsuction point opens into a section of the mixing tube situated upstreamof the diffuser.
 18. The suction jet pump of claim 14, wherein thesecond suction point is arranged in the area of the first suction pointrelative to the axial extent of the suction jet pump.
 19. The suctionjet pump of claim 14, wherein the second suction point is located at alocation on a periphery of the suction jet pump separated by an angle of20° to 180° from a location of the first suction point about alongitudinal axis of the suction jet pump.
 20. The suction jet pump ofclaim 19, wherein the angle is between 90° and 180°.
 21. The suction jetpump of claim 14, wherein a longitudinal axis of the second suctionpoint is perpendicular to a longitudinal axis of the mixing tube. 22.The suction jet pump of claim 14, wherein a longitudinal axis of thesecond suction point is arranged at an angle to a longitudinal axis ofthe mixing tube that is non-perpendicular.
 23. The suction jet pump ofclaim 14, wherein the second suction point is integrally formed with thesuction jet pump as only one single piece.
 24. The suction jet pump ofclaim 23, wherein the second suction point is embodied as a connectionto which a line for conducting fluid is connectable.
 25. The suction jetpump of claim 14 wherein the second suction point is embodied as a bore,into which a line for conducting fluid is insertable.
 26. The suctionjet pump of claim 14, wherein the connection of the motive fluid line isarranged in a radial orientation relative to a longitudinal axis of thesuction jet pump and the second suction point has the same radialorientation as the connection.
 27. The suction jet pump of claim 16,wherein the diffuser is a separate component configured to connect tothe mixing tube.
 28. The suction pump of claim 27, wherein the diffuseris connectable to the mixing tube by a snap-socket connection.